add python test code with pyodbc

src/connector/odbc/tests/odbc.py

+import pyodbc
+cnxn = pyodbc.connect('DSN=TAOS_DSN;UID=root;PWD=taosdata', autocommit=True)
+cnxn.setdecoding(pyodbc.SQL_CHAR, encoding='utf-8')
+#cnxn.setdecoding(pyodbc.SQL_WCHAR, encoding='utf-8')
+#cnxn.setencoding(encoding='utf-8')
+cursor = cnxn.cursor()
+cursor.execute("SELECT * from db.t")
+row = cursor.fetchone() 
+while row: 
+    print(row)
+    row = cursor.fetchone()
+